Pulpstone



June 18, 1940. LEAFE 2,205,296

PuLPsToNFA Filed March 2, 1939 3Min/nm EHRL L. Lem-E Fla-.4 Y

Patented June 18, 1940 TEQ prrr.

PULPSTONE rvCarl L. Leafe, Hamiiton, Ontario, Canada, as- 5 signor 'to Norton Company, Worcester, Mass., a corporation of Massachusetts Application March 2, 1939, Serial No. 259,401

` 1 claim. (c1. 51-207) The invention relates to fpulpstones.

One object of the invention is to prevent the wearing away of the inner concrete portions of the pulpstone just outside of the holding flanges. Another object of the invention is 'to grind away any wood splinters that may be jammed between the stone and the frame. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claim.

In the accompanying drawing illustrating one of many possible embodiments of the mechanical features of this invention,

Figure 1 is an axial sectional View of a pulpstone constructed in accordance with the invention, the section being taken along the line l-i of Figure 2.

Figure 2 is an end elevation of the pulpstone.

Figure 3 is an elevation of a protective plateV which is more specifically the subject of the present invention, and

Figure 4 is a sectional view taken on the line li-ll of Figure 3. 'I

Referring rst to Figure 1 there is therein illustrated a pulpstone which excepting for the features to be specifically pointed out is made in accordance with the disclosure in United States Letters Patent No. 1,920,204 to Thure Larsson. The protective plates of the present invention may, however, be applied to other types of pulpstone, for example that disclosed in Patent 2,141,608 to Thure Larsson.

Still referring to Figure 1, the pulpstone may be mounted upon a central shaft I which is threaded at the portions II and has flanges. l2 to grip the stone. It has been customary for the mills to use flanges I2 which are somewhat smaller in diameter relatively speaking than those disclosed in the aforesaid Patent No. 1,920,204 to Larsson. The pulpstone further consists of bonded abrasive segments or sectors I3 secured by elastic tension bolts Ill to a `central steel cylinder I5. The bolts I4 are secured to the segments I3 by wedge blocks I5 which t between dove-tailed portions of the segments I3, all as described in the patent referred to. Concrete I6 is poured between the cylinder` I5 and the segments I3 and forms the whole into a monolith. An inner steel hub 20 is connected to the cylinder I by another concrete mass 2l and centering bolts 22 are provided axially to center the stone upon the shaft I0. The foregoing is describedv in greater detail in the Patent No. 1,920,204 referred to and the severa-'l advanta-l geous features thereof are fully explained therein.

As aforesaid the flanges I2 Whichare supplied by the user of the pulpstone have in many cases, for one reason or the other, been of a diameter less than that of the concrete portion I6. Since the concrete portions of the stone are much less resistant to wear than the 'ceramically bonded and vitried abrasive segments I3, the concrete has been subject to abrasion due to the continual presence of grinding water with abrasive particles therein. Wood splinters become lodged between the stone and the frame of the pulp grindler and constitute a hazard and, carrying entrained abrasive as they do, increase the abrasive action upon the concrete.

Referring now especially to Figures 2, 3 land 4, I provide abrasive plates 25. These are generally segmental in shape or as actually shown constitute a five sided figure having a straight edge 26, a pair of similar edges 2l at an obtuse angle to the edge 26 and a pair of similar edges 28 substantially at right angles to the edges 21 with a protruding semi-circular portion 29 joining edges 28, and in the short dimension as shown in Figure 4 constituting a rectangle modified by rectangular projections 30 leaving rectangular grooves 3|. These plates 25 may be made of the same material as the segments I3, that is to say of abrasive bonded with vitrified ceramic bond and fired in a kiln. The abrasive may be fused alumina, emery or corundum, or silicon carbide, or any other desired type. I might bond the abrasive for the plates 25 with ceramic bond, for example with synthetic resin or with rubber yor sodium silicate might be used, but vitrii-ied ceramic bond is preferred.

The plates 25 are located in the Wheel as` clearly disclosed in Figures 1 and 2 with the projections 30 extending into the concrete i6 and the concrete I6 extending into the grooves 3|. In other Words a set of plates 25 is placed at the bottom of the stone as the concrete I6 is being poured, and when the pouring has been finished and the concrete is still soft another set of plates at the other end are placed in position. The lines 26 of the plates 25 terminate at the flanges I2, that is to say the lines 25 are substantially tangent to the flanges. I prefer this construction because then the flanges will not grip the abrasive material but will rather grip the concrete and this saves wear on the flanges.

"til,

However in certain cases the plates 25 may extend under the anges l2 and the anges may grip the plates 25 and thereby a rm driving action is secured.

By the provision of the plates 25, wearing away of the concrete I6 is altogether eliminated and the plates 25 will last as long as the stone does because they are subjected only to incidental abrasion and not to regular grinding action. Any splinters which enter between the frame and the ends of the stone will be quickly ground Au p and thereby removed. This in operating the stone as well as reducing the wear thereof. The semi-circular projections 29 of the plates 25 cover the concrete which covers the ends of the wedge blocks I5.

It will thus be seen there has been provided by this invention an article in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible` embodiments may be made of the above invention and as many changes might be made in the embodiment set forth it is to be understood that all matter hereeliminates hazards inbefore set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

I claim:

A pulpstone assembly comprising a central shaft, threaded portions on said shaft, internally threaded flanges screwed onto said threaded portions, a pulpstone between said flanges comprising a hollow generally cylindrical concrete center portion, a plurality of abrasive segments surrounding said concrete center portion, means securing said bonded abrasive segments to said concrete center portion, there being a gap in a radial direction between the segments and the peripheries of the anges, and a plurality of protective abrasive plates embedded in the concrete whose surfaces are substantially in radial planes, and which collectively substantially cover the gap between the flanges and the bonded abrasive segments, constituting protective devices for the concrete and capable of grinding any wood splinters that approach the axis of the stone.

CARL L. LEAFE. 

